Reach
Aussi : Unique reach, Net reach, Audience reach, Portee, Couverture
The number of unique people exposed to your message in a given period. Unlike impressions, reach counts each person once, no matter how often they see it.
What It Is
Reach is the count of unique individuals exposed to a message, campaign, or content during a defined time window. The key word is *unique*: if one person sees an ad five times, they add 1 to reach and 5 to impressions. Reach answers the question "how many people did we touch?" while impressions answer "how many times was it served?"
Reach is usually expressed as:
- An absolute number (for example, 2.4 million people)
- A percentage of a target population (for example, 38% of adults 25 to 54 in a market)
Why it matters
Reach measures the breadth of exposure and is a core input for planning and evaluation:
- Awareness building: new products and brands need broad reach before conversion can scale.
- Deduplication: because it removes double counting, reach is a truer measure of audience size than raw impressions.
- Efficiency ceiling: once you have reached most of your addressable audience, extra spend mostly increases frequency (repeat exposures), not reach.
How it is used in practice
- Frequency pairing: reach is almost always read alongside average frequency. `Impressions = Reach x Average Frequency`. Planners set a target frequency (often 3 to 10 exposures) and solve for the reach a budget can buy.
- Incremental reach: when adding a channel, the useful metric is *net new* reach, the unique people not already reached elsewhere.
- Effective reach: the share of the audience reached at least N times (the minimum thought to drive an effect).
- Cross-platform measurement: deduplicating reach across TV, social, and web is hard and is where identity resolution and panel or modeled data come in.
Worked Example
A campaign is served 900,000 impressions. Log analysis shows the ad was seen by 300,000 unique people.
- Reach = 300,000
- Average frequency = 900,000 / 300,000 = 3.0
If the target market is 1,000,000 people:
- Reach % = 300,000 / 1,000,000 = 30%
Adding a second channel serves 400,000 impressions to 250,000 people, but 100,000 already saw the first channel. The incremental reach is only 150,000, lifting total unique reach to 450,000 (45%). This shows why stacking channels yields diminishing unique audience even as impressions climb.
Common Pitfalls
- Confusing reach with impressions or clicks.
- Summing per-channel reach without deduplication (double counts people).
- Chasing reach when the campaign goal is conversion, where frequency and targeting matter more.